Ocean Mercury Levels Have Tripled Since the Industrial Revolution

An alarming new study shows that mercury levels near the surface of many of the world’s oceans have tripled since the industrial revolution. The leap is due to pollution from a variety of sources including mines, coal-fired power plants and sewage. The study stops short of warning against human consumption of seafood, but it does warn of damage to marine life – and one scientist calls it “an alarm call for the future.”

According to a letter published in the peer-review journal Nature, the mercury content of shallow ocean layers has tripled since the industrial revolution. As we pour the element into the atmosphere and the seas, mercury is accumulating in the surface layers faster than in the deep ocean. The toxic metal will disperse to lower layers in time, but this can take decades. The study also showed that deep waters in the North Atlantic have a higher mercury content than deep waters in the South Atlantic and the Southern and Pacific Oceans. And unfortunately, the north pole and the Arctic circle will probably bear the biggest brunt – winds and ocean currents carry pollutants released elsewhere in the world to these areas, where they accumulate in top predators such as polar bears.

The scientists behind the letter, including researchers from the prestigious Woods Hole Oceanographic Institution, stopped short of warning about the dangers to human health from all the mercury accumulating in the oceans. Simon Boxall, lecturer on ocean and earth science at the University of Southampton, said it was “hard to say” from the research how much damage had already been done to marine life, including edible fish species, and how quickly any such damage would become apparent. “I would not stop eating ocean fish as a result of this,” he said. “But it is a good indicator of how much impact we are having on the marine environment. It is an alarm call for the future.”